Various materials have been developed in recent years for utilization in optical articles which require a high degree of thermal stability. Certain composites are particularly attractive in this regard, especially when the article's weight and its time and cost of fabrication are important considerations. Laser mirrors, and especially such mirrors intended for use with high energy lasers and possibly in the remoteness of outer space, have found such thermally stable composite materials to be advantageously used in their construction.
An example of a particularly suitable composite material utilized in the formation of a laser mirror is disclosed in U.S. Pat. No. 4,256,378 issued Mar. 17, 1981 to K. M. Prewo et al for Graphite-Glass Composite Laser Mirror. That application discloses a laser mirror comprised of a graphite fiber/glass matrix composite. That composite material provides a laser mirror of low density, high elastic stiffness, high strength, high fracture toughness, low thermal expansion, high thermal conductivity and environmental stability.
Although the graphite fiber/glass matrix composite disclosed in the aforementioned U.S. Pat. No. 4,256,378 permits the formation of laser mirrors which exhibit a relatively high degree of dimensional stability over a relatively wide temperature range, the demanding requirement for maintaining precise optical alignment in a laser optical system affords room for even greater improvement.
Accordingly, it is a principal object of the present invention to provide a method by which an optical article comprised of a graphite fiber/glass matric composite may exhibit increased dimensional stability, particularly during exposure to certain operating environments. Included within this object is the provision of such method for use with laser mirrors comprising in at least significant part a graphite fiber/glass matrix composite.
It is a further object of the present invention to provide a relatively practical method for increasing the dimensional stability of a graphite fiber/glass matrix composite laser mirror during operation.